Conceived as a way to replace traditional construction material and increase the eco-value of commercial and residential buildings, globally the Building Integrated Photovoltaic (BIPV) solution has grown in popularity.
By seasoned architect Olufemi Ogunkeye, CEO of Innovation City Ventures and BIPV expert
Based simply on integrating PV materials with the architecture of the building, BIPV is an innovative solution from an economic standpoint for new construction, and potentially existing ones. As such, BIPV technology is under rapid development, which will in turn have a positive impact on prices in the near future.
However, as interesting an option as this presents, it is most viable when taken into consideration from the very beginning of the building’s design phase. For instance, for BIPV to operate efficiently and to reduce losses, shadow from surrounding objects and buildings must be taken into consideration during the design process. Other factors to consider when exploiting surfaces to gain energy efficiency are the PV modules’ orientation and slope.
Benefits of BIPV application
- BIPV is sometimes the optimal method of installing renewable energy systems in urban, built-up areas where undeveloped land is both scarce and expensive
- Efficient use of the building facade area
- Energy delivered ‘on the spot’ (no transmission losses)
- Lots of possibilities for architectural design
- Modern and ecologic appearance of the buildings
- Savings on building materials (the solar panels could replace roofs, walls, windows and shutters)
Where to apply BIPV?
a) Above sloped roof
b) In sloped roof
c) On flat roof
d) Tilted in front of façade
e) In facade sawtoothed roof
f) On flat roof
g) Layered shutters
BIPV modules could have different appearances:
• Different colours
• Different structures
• Different glasses (athermic glasses, anti-burglary, etc.)
Installation demonstration using roofing shingle (RS) PV module
In this case study, the manufacture of RS PV modules is based on a recently developed technology for solar cells encapsulation within glass fibre-reinforced composite materials. By means of this new technology, cell encapsulation within composite materials takes place in a single step, yielding a self-supporting, monolithic and lightweight PV module. Curved and complex geometries can be obtained, opening a wide range of new BIPV products with enhanced building integration possibilities.
Moreover, by using a composite material, in which the cells and their connections are completely embedded, the need to use additional materials as a base or covering is eliminated. Protective coating materials can also be added, either onto the mould during the manufacturing process, or afterwards.
The resulting PV modules present advanced characteristics in terms of structural capacity, transparency, adaptability to nonplanar geometries, protection, weight and reduction of stages in the manufacturing process, as well as issues concerning transport,manipulation, assembly, safety and security. The RS unit was designed to be easily handled thanks to a low weight and a reasonable size. The RS element is a frameless rectangular monocrystalline silicon solar panel with characteristic sawtooth-shaped profile as shown in Figure 1.
The RS PV module has dimensions 905 x 1395 x 59mm and weighs 7.3kg. From the manufacturing process, it is an opaque module, which is later painted black to reproduce the colour of the natural slate of the roof.
The shape of the modules required a special installation technique in order to simplify the installation. All 57 modules were installed in one day. From top to the bottom, the modules overlap to form one large continuous PV surface to cover the roof’s area (both the main and secondary part of the roof). From left to right there are no joints in between the panels (see Figure 2) and a hidden gutter is used to collect rainwater.
The roof is first covered with thermal insulation and a wooden structure where the aluminium profiles to fix the PV panels are installed. Thus, an air gap between the PV modules and the substructure is formed in order to cool the panels and avoid loss of efficiency due to overheating. The air gap is naturally ventilated without the use of a fan to drive the air behind the PVs.
In this case, monitoring of the temperature of the PV surface and the power production will aid research to understand if natural ventilation is adequate to cool the PV surface or a fan to drive the hot air outside the duct is needed (see Figure 3).